It will take at least a year of computer processing time to go through all the data produced. But it will be worth it. The topographic maps of Earth will be 30 times as precise as the best global maps in use today.

'Spectacular' science

The information about height variations on land will aid studies of earthquakes, volcanoes and climate change. It will also assist in land and forest management, as well as being of great use to the military.

"The science on this flight is going to be spectacular," said astronaut Janice Voss, who will be in charge of the radar. "The 3D map of 80% of the surface of the Earth, we think, is going to be a really great product to bring back for everybody on this planet."

The crew will be in space for 11 days

Space-radar mapping missions have been flown several times before, but scientists say the mission data will be especially valuable because the information will be consistent for the whole globe. They point out that the consistency of data collected by spacecraft means probes sent to Venus and Mars have produced better maps than are currently available for the Earth.

The Endeavour flight was originally set for launch last September but was delayed while Nasa checked the shuttle fleet for wiring problems. This followed a short-circuit that disabled two computers during a launch of Columbia last year.

Highly accurate

This SRTM imaging system will orbit 233 kilometres (145 miles) above Earth, with two radar antennas mounted in the shuttle payload bay and two extended on the mast.

German astronaut Gerhard Thiele has trained for three years for this mission

The radar will image vast, barren deserts, frozen tundra, and deep valleys carved by glaciers, such as those found in Alaska, the Andes, and the Himalayas.

The 13-tonne radar system will be able to collect highly accurate, high-resolution images of the Earth's crust between 60 degrees north latitude and 56 degrees south latitude. The regions to be mapped are home to about 95% of the world's population and will be captured to an accuracy of less than 30 metres (100 feet).

Endeavour is set to blast off from Cape Canaveral, Florida, at 1747 GMT on Monday.